Migrate configuration_field() to SkylarkCallable.

Previously this was a member of SkylarkAttr, which didn't make much sense, as the function was not under the attr namespace. This moves configuration_field to a new spot for global functions, "SkylarkBuildApiGlobals".

RELNOTES: None.
PiperOrigin-RevId: 193253435

3 files changed, 73 insertions, 50 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkAttr.java b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkAttr.java
index 4afe8c29d6..423fab890a 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkAttr.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkAttr.java
@@ -41,9 +41,7 @@ import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkPrinter;
-import com.google.devtools.build.lib.skylarkinterface.SkylarkSignature;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
-import com.google.devtools.build.lib.syntax.BuiltinFunction;
 import com.google.devtools.build.lib.syntax.Environment;
 import com.google.devtools.build.lib.syntax.EvalException;
 import com.google.devtools.build.lib.syntax.EvalUtils;
@@ -52,7 +50,6 @@ import com.google.devtools.build.lib.syntax.Runtime;
 import com.google.devtools.build.lib.syntax.SkylarkCallbackFunction;
 import com.google.devtools.build.lib.syntax.SkylarkDict;
 import com.google.devtools.build.lib.syntax.SkylarkList;
-import com.google.devtools.build.lib.syntax.SkylarkSignatureProcessor;
 import com.google.devtools.build.lib.syntax.SkylarkType;
 import com.google.devtools.build.lib.syntax.SkylarkUtils;
 import com.google.devtools.build.lib.syntax.Type;
@@ -537,49 +534,6 @@ public final class SkylarkAttr implements SkylarkValue {
         env);
   }
 
-  @SkylarkSignature(
-    name = "configuration_field",
-    returnType = SkylarkLateBoundDefault.class,
-    // TODO(cparsons): Provide a link to documentation for available SkylarkConfigurationFields.
-    doc = "References a late-bound default value for an attribute of type "
-      + "<a href=\"attr.html#label\">label</a>. A value is 'late-bound' if it requires "
-      + "the configuration to be built before determining the value. Any attribute using this "
-      + "as a value must <a href=\"../rules.html#private-attributes\">be private</a>.",
-    parameters = {
-        @Param(
-            name = "fragment",
-            type = String.class,
-            doc = "The name of a configuration fragment which contains the late-bound value."
-        ),
-        @Param(
-            name = "name",
-            type = String.class,
-            doc = "The name of the value to obtain from the configuration fragment."),
-    },
-    useLocation = true,
-    useEnvironment = true
-  )
-  private static final BuiltinFunction configurationField =
-      new BuiltinFunction("configuration_field") {
-        public SkylarkLateBoundDefault<?> invoke(
-            String fragment, String name, Location loc, Environment env)
-            throws EvalException {
-          Class<?> fragmentClass = SkylarkUtils.getFragmentMap(env).get(fragment);
-
-          if (fragmentClass == null) {
-            throw new EvalException(
-                loc,
-                String.format("invalid configuration fragment name '%s'", fragment));
-          }
-          try {
-            return SkylarkLateBoundDefault.forConfigurationField(
-                fragmentClass, name, SkylarkUtils.getToolsRepository(env));
-          } catch (SkylarkLateBoundDefault.InvalidConfigurationFieldException exception) {
-            throw new EvalException(loc, exception);
-          }
-        }
-      };
-
   @SkylarkCallable(
     name = "string",
     doc = "Creates an attribute of type <a href=\"string.html\">string</a>.",
@@ -1708,8 +1662,4 @@ public final class SkylarkAttr implements SkylarkValue {
       printer.append("<attr." + name + ">");
     }
   }
-
-  static {
-    SkylarkSignatureProcessor.configureSkylarkFunctions(SkylarkAttr.class);
-  }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkBuildApiGlobals.java b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkBuildApiGlobals.java
new file mode 100644
index 0000000000..a8851c92c4
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkBuildApiGlobals.java
@@ -0,0 +1,72 @@
+// Copyright 2018 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.analysis.skylark;
+
+
+import com.google.devtools.build.lib.events.Location;
+import com.google.devtools.build.lib.skylarkinterface.Param;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkGlobalLibrary;
+import com.google.devtools.build.lib.syntax.Environment;
+import com.google.devtools.build.lib.syntax.EvalException;
+import com.google.devtools.build.lib.syntax.SkylarkUtils;
+
+/**
+ * A collection of global skylark build API functions that belong in the global namespace.
+ */
+@SkylarkGlobalLibrary
+public class SkylarkBuildApiGlobals {
+
+  @SkylarkCallable(
+    name = "configuration_field",
+    // TODO(cparsons): Provide a link to documentation for available SkylarkConfigurationFields.
+    doc = "References a late-bound default value for an attribute of type "
+      + "<a href=\"attr.html#label\">label</a>. A value is 'late-bound' if it requires "
+      + "the configuration to be built before determining the value. Any attribute using this "
+      + "as a value must <a href=\"../rules.html#private-attributes\">be private</a>.",
+    parameters = {
+        @Param(
+            name = "fragment",
+            type = String.class,
+            named = true,
+            doc = "The name of a configuration fragment which contains the late-bound value."
+        ),
+        @Param(
+            name = "name",
+            type = String.class,
+            named = true,
+            doc = "The name of the value to obtain from the configuration fragment."),
+    },
+    useLocation = true,
+    useEnvironment = true
+  )
+  public SkylarkLateBoundDefault<?> configurationField(
+      String fragment, String name, Location loc, Environment env)
+      throws EvalException {
+    Class<?> fragmentClass = SkylarkUtils.getFragmentMap(env).get(fragment);
+
+    if (fragmentClass == null) {
+      throw new EvalException(
+          loc,
+          String.format("invalid configuration fragment name '%s'", fragment));
+    }
+    try {
+      return SkylarkLateBoundDefault.forConfigurationField(
+          fragmentClass, name, SkylarkUtils.getToolsRepository(env));
+    } catch (SkylarkLateBoundDefault.InvalidConfigurationFieldException exception) {
+      throw new EvalException(loc, exception);
+    }
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkModules.java b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkModules.java
index 3ed8e1003d..17129ee6f4 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkModules.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkModules.java
@@ -39,6 +39,7 @@ public final class SkylarkModules {
   public static final ImmutableList<Class<?>> MODULES =
       ImmutableList.of(
           SkylarkAttr.class,
+          SkylarkBuildApiGlobals.class,
           SkylarkCommandLine.class,
           SkylarkNativeModule.class,
           SkylarkRuleClassFunctions.class);